diff --git a/llvm/test/tools/llvm-objdump/long-option-style.test b/llvm/test/tools/llvm-objdump/long-option-style.test
new file mode 100644
--- /dev/null
+++ b/llvm/test/tools/llvm-objdump/long-option-style.test
@@ -0,0 +1,21 @@
+## Don't make symlinks on Windows.
+# UNSUPPORTED: system-windows
+
+# RUN: rm -rf %t
+# RUN: mkdir %t
+# RUN: ln -s llvm-objdump %t/objdump
+# RUN: ln -s llvm-objdump %t/objdump-11
+
+# RUN: llvm-objdump --help
+# RUN: llvm-objdump -help
+
+## -long-option does not fit with grouped short options.
+## Disallow them in objdump mode.
+# RUN: %t/objdump --help
+# RUN: not %t/objdump -help 2>&1 | FileCheck --check-prefix=UNKNOWN %s
+
+## objdump may be suffixed by a version.
+# RUN: %t/objdump-11 --help
+# RUN: not %t/objdump-11 -help 2>&1 | FileCheck --check-prefix=UNKNOWN %s
+
+# UNKNOWN: Unknown command line argument '-help'.
diff --git a/llvm/tools/llvm-objdump/llvm-objdump.cpp b/llvm/tools/llvm-objdump/llvm-objdump.cpp
--- a/llvm/tools/llvm-objdump/llvm-objdump.cpp
+++ b/llvm/tools/llvm-objdump/llvm-objdump.cpp
@@ -2339,9 +2339,11 @@
   // Register the target printer for --version.
   cl::AddExtraVersionPrinter(TargetRegistry::printRegisteredTargetsForVersion);
 
+  // If called objdump, follow GNU long option style and reject -long-option.
+  StringRef Stem = sys::path::stem(argv[0]);
+  bool LongOptionsUseDoubleDash = Stem.startswith("objdump");
   cl::ParseCommandLineOptions(argc, argv, "llvm object file dumper\n", nullptr,
-                              /*EnvVar=*/nullptr,
-                              /*LongOptionsUseDoubleDash=*/true);
+                              /*EnvVar=*/nullptr, LongOptionsUseDoubleDash);
 
   if (StartAddress >= StopAddress)
     reportCmdLineError("start address should be less than stop address");